Preparation of onion-like Pt-terminated Pt–Cu bimetallic nano-sized electrocatalysts for oxygen reduction reaction in fuel cells

• An onion-like Pt-terminated Pt–Cu electrocatalyst (Pt/Cu/Pt/C) was synthesized.
• Pt/Cu/Pt/C showed high electrochemical activity toward oxygen evolution reaction.
• Excellent stability of Pt/Cu/Pt/C was observed in half-cell and single-cell tests.

Onion-like Pt-terminated Pt–Cu bimetallic nano-sized electrocatalysts (Pt/Cu/Pt/C) were synthesized by using an electroless deposition method. The synthesized Pt/Cu/Pt/C consisted of a Pt-enriched shell, a sandwiched Pt–Cu alloy layer, and a Pt core. The Pt/Cu/Pt/C showed higher electrocatalytic activity toward oxygen reduction reaction in half-cell test than that of commercial Pt/C due to an electronic structure change in the Pt-enriched shell, resulting from the sandwiched Pt–Cu alloy layer underneath. The stability of the Pt/Cu/Pt/C was examined by using both half-cell and single-cell degradation tests. In both tests, the Pt/Cu/Pt/C exhibited stronger resistance to catalyst degradation than that of the commercial Pt/C. It is notable that cell performance with the Pt/Cu/Pt/C was fully recovered by N2 purging after single-cell degradation testing, indicating there was no permanent damage to the electrocatalyst during the test. It is suggested that thermodynamically-stable structure of the Pt/Cu/Pt/C contributed to the improved stability.

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